The present invention relates to calendar electronic timepieces that are capable of indicating a date, and more particularly to a calendar electronic timepiece that can rotate a date dial with high torque by using an ultrasonic motor and accurately position a date character of the date dial in position.
In a conventional calendar electronic timepiece having a single motor, a battery 902 constitutes a power source, for example, as shown in FIG. 21. An IC 904 is connected to the battery 902 to count time information about a time and date, etc. A timepiece motor 906 rotates, for example, by 180 degrees per second based on a time information signal outputted by the IC 904. A multistage reduction wheel train 908 is formed by a plurality of gears. The multistage reduction wheel train 908 reduces and transmits the speed of the timepiece motor 906 to rotate a hand driving wheel 910. Time information, e.g. "hour", "minute" and "second", is indicated by the hand driving wheel 910 formed respectively by an hour pointer, a minute pointer and a second pointer.
A date dial 912 is intermittently operated by the multistage reduction wheel train 908 to indicate a "date" by a character of from "1" to "31" provided on indicating surfaces of the date dial 912.
In a conventional calendar electronic timepiece having a plurality of motors, a battery 902 constitutes a power source, for example, as shown in FIG. 22. An IC 904 is connected to the battery 902 to count time information about a time and date, etc. A timepiece motor 906 rotates, for example, by 180 degrees per second based on a time information signal outputted by the IC 904. A reduction wheel train (not shown) is formed reduces and transmits the speed of the timepiece motor 906 to rotate a hand driving wheel 910. Time information, e.g. "hour", "minute" and "second", is indicated by the hand driving wheel 910 formed respectively by an hour pointer, a minute pointer and a second pointer.
A date dial motor 914 is rotated based on date information signal outputted by the IC 904. A multistage reduction wheel train 916 reduces and transmits the speed of a date dial motor to rotate a date dial 912. A "date" is indicated by a character of from "1" to "31" provided on indicating surfaces of the date dial 912.
In a conventional calendar electronic timepiece having a plurality of motors, a date dial motor 914 includes a coil block 918 for the date dial motor, a date dial stator 920, and a date dial stator 922, as shown in FIG. 23 and FIG. 24. A multi-stage reduction wheel train 916 includes a first transmitting wheel 924, a second transmitting wheel 926, and a date driving wheel 928. The date driving wheel 928 is in mesh with a tooth portion 912a of a date dial. Numerals of from "1" to "31" are provided on indicating surfaces 912b of the date dial.
An IC 904 counts time information about a time and date, etc. When outputting a result of the count of 0 o'clock a.m., the date dial motor 914 rotates based on the time information signal outputted by the IC 904. This turns, through the first transmitting wheel 924, the second transmitting wheel 926 and the date dial wheel 928, the date dial 912 by 360.degree./31, i.e. a 1/31 rotation.
Furthermore, in an analog-type electronic timepiece using an ultrasonic motor as a timepiece motor 906, time is indicated by an hour pointer, a minute pointer, and a second pointer through a wheel train driven by a moving body of the ultrasonic motor. For example, there is disclosed, e.g. in Japanese Laid-Open Patent Publication No. H2-287281, a structure of an analog-type electronic timepiece using a standing-wave type ultrasonic motor.
Further, in an electronic appliance using a conventional ultrasonic motor and an ultrasonic motor, there is provided a vibrating member joined with a piezoelectric element so that the moving body is frictionally driven by vibrating waves generated in the vibrating member due to expansion and contraction of the piezoelectric element. A pressure applying means causes the moving body to be pressure-contacted with the vibrating member. An oscillation driving circuit applies a drive signal to an electrode group formed in the piezoelectric element. This drive signal causes the piezoelectric element to expand, generating vibrating waves on the vibrating member. The vibrating waves cause the moving body to be frictionally driven. The structure of an electronic appliance using the conventional ultrasonic motor and the ultrasonic motor is disclosed, e.g. in Japanese Laid-Open Patent Publication No. H8-251952.
In a conventional calendar electronic timepiece having a date driving motor, a wheel train is provided, at a part thereof, with a 24-hour contact 932 for detecting a rotational position of the wheel train 930, as shown in FIG. 25. When the 24-hour contact 932 detects a position corresponding to 0 o'clock a.m., the 24-hour contact 932 outputs a detection signal by which a circuit block 934 causes the date driving motor 936 to rotate. The rotation of the date driving motor 936 rotates the date dial 912 through a reduction wheel train 938. This makes possible change of date indication.
Furthermore, in a calendar electronic timepiece having a CPUIC, a circuit block (CPUIC) 940 counts time, as shown in FIG. 26. When counting by 24 hours, the date driving motor 936 is rotated. The rotation of the date driving motor 936 causes the date dial 912 to rotate through rotation of the reduction wheel train 938. This makes possible change of date indication.
However, there have been problems in the conventional calendar electronic timepieces, as below.
(1) The conventional calendar electronic timepiece having a single motor cannot accurately rotate only the date dial at a high speed.
(2) The conventional calendar electronic timepiece having a plurality of motors requires a coil block for a date dial motor, a stator for the date dial motor, a rotor for the date dial motor and a multi-stage reduction wheel train having a multiplicity of gears, thereby increasing the size of the timepiece. This makes it substantially impossible to manufacture watches for women.
(3) The conventional calendar electronic timepiece having a plurality of motors also is slow in rotational speed of the date dial, that is, it takes long in moving the calendar.
(4) The conventional calendar electronic timepiece having a plurality of motors further is small in drive torque to the date dial. This in turns, makes it impossible to provide a date jumper for rectifying the position of the date dial.
(5) The conventional calendar electronic timepiece having a plurality of motors further requires a multiplicity of multi-stage reduction wheel trains. Accordingly, the date dial is difficult to accurately align the position due to backlash for each wheel train.
(6) In the conventional calendar electronic timepiece having a 24-hour contact for detecting a rotational position of the wheel train, there are a number of wheel trains arranged from the wheel train to the date dial. Accordingly, the date dial is difficult to accurately align the position due to backlash for each wheel train.
(7) The conventional calendar electronic timepiece having a CPUIC is difficult to indicate a correct date in an event that malfunction occurs in rotation of the date driving motor.